The Drag and Drop Component Suite for Delphi

1 votes, average: 5 out of 5

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Status

Latest version: 5.1
Released: 29 jan 2010
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The Drag and Drop Component Suite is a freeware VCL component library that enables your Delphi and C++Builder applications to support COM based drag and drop and integrate with the Windows clipboard.

The drag and drop system that is built into the VCL, is limited in that it only supports drag and drop within the same application. If you need to drag data from your application to other applications (e.g. Word, Explorer or Outlook), or if you need to be able to accept data dropped from other application (e.g. the Explorer), you have to use COM based drag and drop. COM based drag and drop is an integral and very important part of the Windows user interface and the Drag and Drop Component Suite makes it very easy to leverage all the features of COM based drag and drop in your own Delphi and C++Builder applications.

Every drag and drop operation involves two objects: A drop source and a drop target. The drop source provides the data to be dragged, and the drop target accepts the dragged data.
Likewise there are basically two sets of components in the Drag and Drop Component Suite; Drop source components and drop target components. Most of the source and target components are specialized to handle just one type of data, but a few of the components supports a wider range of data types or are completely generic.

In addition to the drag and drop components, the Drag and Drop Component Suite also includes components that can be used to build Windows Shell Extensions. While these components aren’t all related to Drag and Drop, they benefit from the Drag and Drop Component Suite framework and allow you to write Windows Shell Extensions with very little code. But most important; I had a lot of fun writing them :-).

Features

Freeware with full source code included.
Enables COM drag-and-drop of any kind of data between applications.
Copy, Move and Link operations.
Clipboard Copy, Cut and Paste support.
Support and implement advanced features such as Delete-on-paste and Optimized Move.
Drag image support.
Supports both Ansi and Unicode data formats, regardless of the version of Delphi used.
Supports asynchronous transfer. Both on the source and target side.
Automatic scrolling of the target window during the drag operation.
Relatively simple to derive custom drag-and-drop components to support other data formats.
~~Extensive, context sensitive help file and~~ detailed demo applications.
Implements the IDropSource, IDropTarget, IDataObject and IAsyncOperation interfaces.
Compatible with Delphi 5-2010.

Components

The Drag and Drop Component Suite contains the following components:

Drop Sources		Drop Targets
TDropFileSource Enables you to drag files and shortcuts from your application to other applications. TDropTextSource Enables you to drag text from your application to other applications. TDropBMPSource Enables you to drag bitmaps from your application to other applications. TDropURLSource Enables you to drag URLs from your application to other applications. TDropPIDLSource Enables you to drag PIDLs (files, folders, shell objects) from your application to other applications. TDropEmptySource A basic drop source component that does not support any data formats on its own. Can be extended with support for any data format through the use of a TDataFormatAdapter component.		TDropFileTarget Enables your application to accept files and shortcuts dropped on it from other applications. TDropTextTarget Enables your application to accept text dropped on it from other applications. TDropBMPTarget Enables your application to accept bitmaps dropped on it from other applications. TDropMetaFileTarget Enables your application to accept meta files dropped on it from other applications. TDropURLTarget Enables your application to accept URLs dropped on it from other applications. TDropComboTarget Enables your application to accept files, shortcuts, text, URLs, meta files, and bitmaps dropped on it from other applications. The component is basically all the above components rolled into one. TDropImageTarget Enables your application to accept meta files, and bitmaps dropped on it from other applications. The component is basically the TDropBMPTarget and the TDropMetaFileTarget components rolled into one. TDropPIDLTarget Enables your application to accept PIDLs (files, folder, shell objects) dropped on it from other applications. TDropEmptyTarget A basic drop target component that does not support any data formats on its own. Can be extended with support for any data format through the use of a TDataFormatAdapter component.

Shell Extensions		Additional
TDropHandler Implements the necessary interfaces required to build Drop Handler shell extensions. A Drop Handler shell extension is used to turn file classes (e.g. all files with a specific extension) into drop targets. TDragDropHandler Implements the necessary interfaces required to build DragDrop Handler shell extensions. A Drop Handler shell extension is used to extend the popup menu which is displayed by the shell when a file is dragged with the right mouse button. TDropContextMenu Implements the necessary interfaces required to build Context Menu Handler shell extensions. A Context Menu Handler is used to extend the shell popup menu which is displayed when a file is right-clicked.		TDataFormatAdapter Used to extends source or target components with support for arbitrary clipboard formats. TDropDummy Helper component used to display drag images.

License

This work is licensed under a
Creative Commons Attribution-Share Alike 3.0 Unported License.

Requirements

The library has been tested with the following versions of Delphi:

D1	D2	D3	D4	D5	D6	D7	D2005	D2006	D2007	D2009	D2010

If you can confirm compatibility with any of the untested versions of Delphi (or C++ Builder for that matter), please let me know and I will update the table.

[Updated 2010-01-31] Added D2006 per user feedback.

C++ Builder

I have done absolutely no testing with C++ Builder so I don’t know if the code works with it or not. That said, according to feedback I have received, the current release should work with C++ Builder.

Download

Download:	The Drag and Drop Component Suite v5.1 - Complete
Version:	5.1
Updated:	29 January, 2010
Size:	518.29 KB
Notes:	Includes component source and demo applications.
Downloads:	478

Download:	The Drag and Drop Component Suite v5.1 - Source
Version:	5.1
Updated:	29 January, 2010
Size:	134.09 KB
Notes:	Includes component source only.
Downloads:	119

Old versions

Old versions can be found on the downloads page.

Installation

If you are using a previous version of The Drag and Drop Component Suite, uninstall that version first.
Unzip the package to a folder of your choice.
In the Packages folder, find the design time package that matches your version of Delphi. Open it in Delphi, Compile and Install.
Locate the Library sub-folder that matches your version of Delphi. Add it to the Delphi library search path.
Optional: Add the Source folder to the Delphi browsing path.

Uninstallation

Open Delphi and uninstall the Drag and Drop Component Suite design time package.
Remove the Library folder from the Delphi library search path.
Remove the Source folder from the Delphi browsing path.
Locate the folder where you installed The Drag and Drop Component Suite and delete that folder.

Change log

Changes since version 4.2:

Version 5.1.20100129 (29-jan-2010)
- Missing paths in package project files for Delphi 6, Delphi 2006 and Delphi 2007.
- Missing Output and search path in a few demo applications.
- The OutlookDemo example application hung or crashed on exit if a message attachment had been opened.
- The MakeRTF function in the DragDropText unit failed to compile with some versions of Delphi.
- PIDLs was not generated automatically from Unicode filenames. This caused the “link” drag operation to fail in most cases.
- DragDetectPlus no longer eats right-click mouse messages.
- TargetAnalyzer example application
  The application now performs an asynchronous drag and can be aborted with the [Esc] key. This change was made to be able to break out of Thunderbird and Firefox’s run-away drag loops.
- SourceAnalyzer example application
  - Error handling improved.
  - The application can now optionally prefetch data at the time of drop, instead of at the time the clipboard format is selected in the list.
  - The application now verifies if the media types offered by the drop source can actually be read from the drop source. An amazing number of applications specify more media type and data formats than they actually support - or doesn’t specify the ones they do support. The prize for most funky behaviour goes to Mozilla Thunderbird 3; It does both.
- OutlookDemo example application
  Handling of attachments simplified.
- ExtractDemo example application
  The application now extract files On-Demand (OnGetData event) instead of when the data is dropped (OnDrop event). This change was made to handle application that require the files to be physically present when ever they query the drop source for the file names.
- The SourceDemo example application no longer demonstrates the use of a popup menu.
  This change was made because TListView’s internal mouse message handling makes it impossible to handle right-click correctly.
Version 5.0.20091206 (6-dec-2009)
- Support for Delphi 2010.
- Six new examples:
  - Outlook Source
    Demonstrates how to drag messages from your application to Outlook.
  - RTF Target
    Demonstrates how to receive RTF text. E.g. from Word, WordPad or the TRichEdit control.
  - Target Analyzer
    Analyzes how a drop target interacts with a drop source. Can be used to determine which data formats a drop target can accept.
  - Unicode
    Demonstrates drag/drop of Unicode text and file names to and from your application. The example works unchanged with all supported versions of Delphi.
  - WM_DROPFILES
    Demonstrates the old, non-COM based, way of handling files dropped from Explorer - just for completeness.
  - TreeViewTarget
    Demonstartes accepting or rejecting a drop based on position within drop target.
- Added TCustomDropTarget.Enabled property.
  The Enabled property specifies if the drop target control can accept dragged data. Setting Enabled to False will cause the drop target to reject all drops without further action.
- The TMessages class (used for Outlook drag/drop) now support sessions. This can be (and is) used to work around the various quirks in Outlook’s interface reference counting mechanism.
- Work around for bug in Outlook Express.
  Drop target now asks drop source (e.g. Outlook Express) for each supported data format in turn instead of all at once.
- Work Around for bug in Bluesoleil Shell Integration.
  We now query the drop source for supported data formats before asking for data.
- TAnsiStringClipboardFormat.GetClipboardFormat has been implemented.
- TCustomDropTarget.PasteFromClipboard no longer clears the data after the OnDrop event has fired.
- Fixed bug in TClipboardFormat.GetData that caused drop targets to reject data after first drop.
- Fixed Ansi/Unicode bug in TTextDataFormat that mainly affected TDropTextTarget.
- All Ansi/Unicode conversion hints and warnings has been removed.
- The default property value of TDropComboTarget.OptimizedMove and TDropFileTarget.OptimizedMove is now declared correctly.
- The Shell IL function imports are now compatible with C++ Builder.
- TStorageDataFormat now support both Ansi and Unicode File Group Descriptors regardless of the version of Delphi used.
- Unicode string list redesigned.
  The solution for Unicode string lists, used for file name lists, that was introduced in version 4.2 has been replaced with a solution that does not require class helpers. This means that the same solution is now employed across all supported versions of Delphi.
  The new Unicode string list does not descend from TStrings but is Assign/AssignTo compatible with it.
  All properties, that previously depended on TWideStringList for Unicode support, now use the new TUnicodeStringList instead.
- The DragDetectPlus function now leave mouse click messages (WM_xBUTTONDOWN, WM_xBUTTONUP, etc) in the message queue.
  This change was made to allow drop source controls to use popup menus.
- URL properties are now of type AnsiString.
- The MakeRTF utility function now support Unicode strings and generate proper RTF formatted text.
- The Text data format now support RTF text by default (i.e. it registers the TRichTextClipboardFormat class).
- The design-time package files have been renamed for Delphi 2005 and later.
Version 5.0.20090208 (8-feb-2009)
- Completed Delphi 2009/Unicode migration.
- Back ported to Delphi 5, 7 and 2007.
- Clipboard format registration has been redesigned to remove various bad designs.
- Fixed harmless memory leak.
- TCustomDropSource.OnGetDragImage event added.
- Fixed resource leak.
- Added work around for broken asynchronous transfer in Windows Shell.
- Added work around for deadlock caused by drag over Delphi IDE while debugging.
- Fixed various minor problems with optimized move.
- The TFileGroupDescriptor*ClipboardFormat, TFileContents*ClipboardFormat and TVirtualFileStreamDataFormat classes has been moved to the DragDropFile unit.
- The T*TextClipboardFormat classes has been moved to the DragDropText unit.
- Fixed bug in CreateIStreamFromIStorage and CreateIStorageOnHGlobal which primarily affected drag/drop from Outlook.
- Fixed leak in TFileGroupDescriptorCustomClipboardFormat.
- Fixed misspelling of “FileGroupDescriptor” - woops
- TFilenameClipboardFormat has been renamed TAnsiFilenameClipboardFormat.
- TFilenameWClipboardFormat has been renamed TUnicodeFilenameClipboardFormat.
- TFilenameClipboardFormat is now an alias for the native (ansi or unicode) format.
- TFilenameMapClipboardFormat has been renamed TAnsiFilenameMapClipboardFormat.
- TFilenameMapWClipboardFormat has been renamed TUnicodeFilenameMapClipboardFormat.
- TFilenameMapClipboardFormat is now an alias for the native (ansi or unicode) format.
- TFileGroupDescriptorClipboardFormat has been renamed TAnsiFileGroupDescriptorClipboardFormat.
- TFileGroupDescriptorWClipboardFormat has been renamed TUnicodeFileGroupDescriptorClipboardFormat.
- TFileGroupDescriptorClipboardFormat is now an alias for the native (ansi or unicode) format.
- Text scrap functionality is no longer enabled by default.
- TTextClipboardFormat has been renamed TAnsiTextClipboardFormat
- TCustomTextClipboardFormat has been renamed TCustomAnsiTextClipboardFormat
- TCustomWideTextClipboardFormat has been renamed TCustomUnicodeTextClipboardFormat
- TTextClipboardFormat is now an alias for the native (ansi or unicode) format.
- TDropTextTarget, TDropTextSource and TTextDataFormat now keeps string data data in the source format and only converts between unicode and ansi on demand.
- The old Text property of TDropTextTarget, TDropTextSource and TTextDataFormat is now named AnsiText.
- The new Text property of TDropTextTarget, TDropTextSource and TTextDataFormat now returns the native string format.
- The RichText, OEMText, CSVText and HTML properties of the TDropTextTarget, TDropTextSource and TTextDataFormat classes are no longer supported and have been removed.
- Major rewrite of the TDropContextMenu component.
- Added TDropContextMenu.OnPrepareMenu event.
- Added TDropContextMenu.FolderPIDL and TDropContextMenu.Folder properties.
- Added support for accelerator keys in owner-draw sub menu items.
- Fixed support for ownerdraw top level menu items.
- The TDragDropHandler.GetFolderPIDL function has been replaced with the FolderPIDL property.
  Note that the component owns and manages the life time of the returned PIDL.
- Added support for cascaded menus.
- TURLClipboardFormat has been renamed TAnsiURLClipboardFormat
- TURLWClipboardFormat has been renamed TUnicodeURLClipboardFormat
- TURLClipboardFormat is now an alias for the native (ansi or unicode) format.
- The Title property of TDropURLTarget, TDropURLSource and TURLDataFormat is now a Unicode string.
- PIDLs are no longer stored and manipulated as strings.
- TDropMultiTarget is no longer supported.
  Use TDropComboTarget or the adapter components instead.
Version 5.0.20080514 (14-may-2008)
- Added const directive to interface parameters.
- Prepared for Delphi 2009/Unicode.
- PIDLs are no longer stored and manipulated as strings.
- Deprecated Netscape data formats.
- Added TFileGroupDescriptorCustomClipboardFormat as common ancestor for TFileGroupDescriptorClipboardFormat and TFileGroupDescriptorWClipboardFormat.
- Back ported to Delphi 5 and Delphi 7.

FAQ - Frequently Asked Questions

Rating: +2

When dragging a file from my application to the Explorer, how can I determine the folder where the file is dropped?

In short, you can’t.

You must understand that the drag/drop API works the same for all applications that uses it, and the Explorer is just like any other application. The drag/drop API provides a framework that facilitates the interaction between a drop source and the target, but since the drop target can do anything it wants with the data it receives, there is no way to communicate the destiny of the data back to the drop source in a uniform way.
One target may chose to display the dropped data (e.g. notepad), another one to upload it to a web server (e.g. a FTP client), a third to move and rename the file (e.g. the Recycle Bin) and a fourth may chose to copy or move the file (e.g. Explorer).

In my experience there is never any real need to know the destination of a drop to the Explorer. If you find that you do need this, you should rethink your solution. - and feel free to ask for help.
Rating: +0

What is the difference between the drop source components’ AllowAsyncTransfer property and the Execute methods’ Asynchronous parameter?

The Execute methods Asynchronous parameter specifies if the source should perform the transfer in a thread.

The AllowAsyncTransfer property specifies if the drop target is allowed to perform an asynchronous transfer.

The two are completely independent. One does not have priority over the other.

Asynchronous transfer on the source side is an “invention” of mine. It can be done even if the drop target doesn’t support, and thus doesn’t take an active part in, asynchronous transfer.

Asynchronous transfer on the target side is a COM drag/drop feature (see IAsyncOperation in MSDN). It requires that both the source and the target support asynchronous transfer. All the Drag and Drop Component Suite components support asynchronous transfer, but apart from Windows Explorer few applications has implemented the feature.
Rating: +4

What is “Optimized Move”?

An optimized move is simply a move operation where the drop target moves the data from the source to the destination location.

In a conventional move operation, the source and the target must cooperate in order to complete the operation. First the target makes a copy of the data at the desired location. Then, when the target has completed copying the data, it hands control back to the source who then deletes the original data. This procedure can be very inefficient because it requires two simultaneous copies of the data.

With an optimized move, the target handles the entire move operation and signals the source that an optimized move took place upon completion.

The Drag and Drop Component Suite supports Optimized Move on both the source and target side.

48 comments »

Michael December 7th, 2009 at 05:32 1 +0

When migrating from pre-5.0 releases, are there any guidelines? Code that needs to be changed, "gotchas" to look out for, etc.
Thanks.

Reply to this comment
1. Anders Melander December 7th, 2009 at 14:03 2 +1
  
  It depends…
  
  If you are using custom drop target or drop source classes, or using the data- and clipboard format classes directly, then things have changed quite a lot. Many classes have been renamed and reimplemented.
  
  If you are just using the standard components then you should be good to go. I have made a great effort to maintain high level backward compatibility.
  
  One thing to look out for is that TDropFileTarget.Files and TDropFileSource.Files is now a custom string list which doesn't descend from TStrings. This will not be a problem in most cases and the compiler will catch it for you if it is. I.e. if it compiles, then it works.
  
  Reply to this comment

David December 8th, 2009 at 19:49 3 --1

When attempting to compile/install the D-and-D Component Suite 5 in D5 I get two errors:

"Cannot find the resource file …DragDropD5.res. Recreated" (which is a minor problem…)

and a fatal error: "Could not create output file …\DropSource.dcu".

The package fails to install.

Is there a problem somewhere?

Reply to this comment
1. Anders Melander December 9th, 2009 at 15:03 4 +0
  
  The missing .res file is normal. Since the .res file will be recreated by Delphi when you open the package, I decided not to include it in the zip file this time. The same goes for the .proj and .group_proj files used by D2005 and later.
  
  The "Cannot create out file…" error is likely caused by a missing folder. The zip file contains a number of empty folders under the DragDrop\Library folder. When you unzipped the file these folders should have been recreated even though they are empty. I known that WinZip, 7-zip and WinRar supports this - did you use something else?
  The Delphi 5 package outputs the binary files (.dcu, .bpl, .dcp) in the DragDrop\Library\Delphi 5 folder. Try creating that folder and recompile the package.
  
  Reply to this comment

David December 9th, 2009 at 19:30 5 +0

Yes, as you said. Now it installs OK. Many thanks!

Reply to this comment

stanleyxu2005 December 12th, 2009 at 23:43 6 +0

great work! would you consider about creating an online svn/cvs repository?

Reply to this comment
1. Anders Melander December 13th, 2009 at 20:43 7 +0
  
  The source currently lives in a StarTeam repository on a SAN hosted by a cluster situated in a nuclear proof bunker. The only downside is that I can only access it through VPN.
  
  It would be nice if I could give the public access to the source, or move the source to a public repository, but I'm afraid there's nothing "in it for me" - only more work.
  
  Reply to this comment

Paulo França December 19th, 2009 at 03:53 8 +0

Excelent component! I'll be using it from now on..
P.S. A lot of demo apps are raising weird exceptions at startup. Please, have a look. I'm using Delphi 7 on Windows 2003 Server R2..
The DropTarget component is working easy and nice as it's supposed to.
Congratulations for your great work!

Reply to this comment
1. Anders Melander December 21st, 2009 at 01:32 9 +0
  
  That is because the forms has been opened (by me) with a newer version of Delphi than the one you are using. It's a quite common problem when working with multiple versions of Delphi.
  
  To resolve the problem just open the forms and save them and then recompile.
  
  Reply to this comment

Fedor Mayek December 19th, 2009 at 13:18 10 +0

Just downloaded and tested some of your demos. In the file source demo I can drag files FROM my application into any Windows Explorer window, except on the desktop. Why? Isn't the windows desktop just another instance of explorer.exe?
What am I missing?

Reply to this comment
1. Anders Melander December 21st, 2009 at 01:37 11 +0
  
  It's a bug.
  One of the classes that converts between filenames and PIDLs has a problem that prevents the "Link" drop kind from working.
  
  I have already fixed it internally and will post a new version ASAP.
  
  Reply to this comment

Simon December 20th, 2009 at 14:08 12 +0

Regarding the SourceDemo

Can the following two kinds of drag'n'drop co-exisit:

1. Drag the ListView items to other applications, eg Explorer (this is a behavior of the SourceDemo)

2. If the user drag'n'drop the ListView items within the ListView, I want the items to be re-sorted.

Please advise. Thank you.

Reply to this comment
1. Anders Melander December 22nd, 2009 at 00:13 13 +0
  That's actually quite easy:
  1. Use a TDropFileTarget component to turn the listview into a drop target.
  2. Set a flag when you start the drag operation (e.g. in your TListView.OnMouseDown handler). Clear the flag when TDropFileSource.Execute returns.
  3. In the TDropFileTarget.OnEnter handler reject the drop unless the flag has been set.
  4. In the TDropFileTarget.OnDrop handler move the currently selected listview items to the drop location. You can use TListView.GetItemAt to find the drop location.
    See also: Rearrange Multiple TListView Items using Drag and Drop.
  Reply to this comment

Philippe Watel December 25th, 2009 at 11:50 14

Thanks for your components it is a wonderful gift To the community but..
it fails to compile so does not install.

[DCC Error] DragDropText.pas(325): E2011 Low bound exceeds high bound

function MakeRTF(const s: string): AnsiString;
...
begin
...
      c := p^;
      cAnsi := AnsiChar(c);
      if (Ord(c) <= 127) then // Char is ANSI
      begin
        case cAnsi of
        '\', '{', '}':
          Result := Result + '\' + cAnsi;
        Chr(9):
          Result := Result + '\tab ';
        Chr(13):
          Result := Result + '\par ';
        Chr(0)..Chr(8),
        Chr(10)..Chr(12),
        Chr(14)..Chr(31),
        Chr(127)..Chr(255):   <<<--- HERE
          Result := Result + AnsiString(Format('\"%.2x', [ord(c)]));
        else
          Result := Result + cAnsi;
        end;
...

I hope you can fix it soon .
Merry Christmas - Peace
Philippe Watel

Reply to this comment

Anders Melander December 25th, 2009 at 23:26 15 +0

Which version of Delphi are you using?

Reply to this comment

vedmaka December 25th, 2009 at 21:27 16 +0

Hello. I trying to make drag&drop images from browser to my program.
using DropComboTarget.

With Firefox it works fine. I get Bitmap and working with it, but with IE and Chrome i got only Text and Url when drop image. I tried to look at Source Analyzer Demo: when i drop image from
Chrome i got "filecontents" and this is content of dropped image, but in DropComboTarget i got only Text & Url … (sorry if my English was bad, hope u understand me )

Reply to this comment
1. Anders Melander December 25th, 2009 at 23:35 17 +0
  
  As far as I can tell this is caused by a bug in IE8 (as far as I remember it used to work in previous versions of IE): IE does offer the FileContents clipboard format, but fails to actually fill it with any data. The Drop Source Analyzer indicates this by drawing the medium (GlobalMem) in red.
  
  If you are seeing something different please state your version of IE and mail me the data format list (select Save list… from the toolbar) from the Source Analyzer.
  
  Reply to this comment
  1. Anders Melander January 29th, 2010 at 16:28 18 +0
    
    Further tests show that IE8 can drag images, but only if the image isn't wrapped in an A tag (i.e. a link). I'm afraid there's nothing I can do about this strange behavior.
    
    (Comments wont nest below this level)
    
    Reply here

Philippe Watel December 25th, 2009 at 23:51 19

hi
delphi 2010 but i tried with 2009 and it was the same
bye
PW

Reply to this comment

Anders Melander December 26th, 2009 at 22:18 20

I'm afraid I can't reproduce your problem with either D2009 or D2010 but try rewriting the case statement like this:

case cAnsi of
  '\', '{', '}':
    Result := Result + '\' + cAnsi;
  Chr(9):
    Result := Result + '\tab ';
  Chr(13):
    Result := Result + '\par ';
  else
    if (Ord(cAnsi) > 31) and (Ord(cAnsi) < 127) then
      Result := Result + cAnsi
    else
      Result := Result + AnsiString(Format('\''%.2x', [ord(c)]));
end;

Reply to this comment

Michael Fu January 4th, 2010 at 04:11 21 +0

We have same error happened as [DCC Error] DragDropText.pas(325): E2011 Low bound exceeds high bound. But It's OK now after modify those code from you.

Reply to this comment
1. Anders Melander January 4th, 2010 at 21:31 22 +0
  
  Thanks for the feedback.
  Although I still cannot reproduce the error I have now applied the change to my source so the problem doesn't reappear.
  
  Reply to this comment

EraM January 11th, 2010 at 20:57 23 +0
Hello!

Delphi 2009, component TDropFileSource.

In popup menu:
- Copy -OK
- Move - OK
- Create Links - do not work
Reply to this comment
1. Anders Melander January 11th, 2010 at 21:04 24 +0
  
  It's a known problem.
  
  I will see if I can find time to upload a new version this week.
  
  Reply to this comment

Paul January 19th, 2010 at 08:45 25 +0

This works beautifully in Delphi 6 but …

I had a lot of trouble getting this to install. I am now having to reinstall my system after a crash and so far have not been able to pesuade Delphi to compile D & D again (yes the folder does exist per above comment by David).

Thank you for this package. I appreciate the work put into its creation as I was part way through trying to work this out myself when I found your components.

Reply to this comment
1. Anders Melander January 19th, 2010 at 09:52 26 +0
  
  What error are you getting from the compiler?
  
  Reply to this comment
  1. Paul January 21st, 2010 at 12:45 27 +0
    
    Thank you for the reply. The error message is
    
    Could not create output file …\DropSource.dcu
    
    On a hunch I tried adding the contents of the source folder to Delphi6\Lib and placing DragDropD6.dpk in the same folder, double clicked on DragDropD6.dpk and it installed.
    
    Hope this helps Paul
    
    (Comments wont nest below this level)
    1. Anders Melander January 21st, 2010 at 15:10 28 +0
      I just checked the Delphi 6 package files and it appears that they were not configured correctly.
      
      With the files back in their original locations try editing the package source files in notepad:
      
      In DragDropD6.dof change the [Directories] section:
      
      [Directories] OutputDir= UnitOutputDir=..\Library\Delphi 6 PackageDLLOutputDir=..\Library\Delphi 6 PackageDCPOutputDir=..\Library\Delphi 6 SearchPath=$(DELPHI)\Lib\Debug;..\Source
      
      In DragDropD6.dpk update the path to the source files:
      {$R *.RES} {$R '..\Source\DragDrop.dcr'} {$R '..\Source\DropSource.dcr'} {$R '..\Source\DropTarget.dcr'} {$R '..\Source\DragDropText.dcr'} {$R '..\Source\DragDropFile.dcr'} {$R '..\Source\DragDropGraphics.dcr'} {$R '..\Source\DragDropPIDL.dcr'} {$R '..\Source\DragDropInternet.dcr'} {$R '..\Source\DropComboTarget.dcr'} {$R '..\Source\DragDropHandler.dcr'} {$R '..\Source\DragDropContext.dcr'} {$R '..\Source\DropHandler.dcr'} ... contains DropSource in '..\Source\DropSource.pas', DropTarget in '..\Source\DropTarget.pas', DragDropPIDL in '..\Source\DragDropPIDL.pas', DragDropFormats in '..\Source\DragDropFormats.pas', DragDropFile in '..\Source\DragDropFile.pas', DragDropText in '..\Source\DragDropText.pas', DragDrop in '..\Source\DragDrop.pas', DragDropGraphics in '..\Source\DragDropGraphics.pas', DragDropInternet in '..\Source\DragDropInternet.pas', DropComboTarget in '..\Source\DropComboTarget.pas', DragDropDesign in '..\Source\DragDropDesign.pas', DragDropHandler in '..\Source\DragDropHandler.pas', DragDropComObj in '..\Source\DragDropComObj.pas', DragDropContext in '..\Source\DragDropContext.pas', DropHandler in '..\Source\DropHandler.pas';
    2. Anders Melander January 21st, 2010 at 15:21 29 +0
      
      The DragDropD2006.dpk and DragDropD2007.dpk files also needs to have their {$R} directives adjusted.
    3. Paul January 22nd, 2010 at 10:34 30 +0
      
      Thank you for the help.
    Reply here

JunP January 21st, 2010 at 11:00 31 +0

Hello,

I have an application which will get all the email addresses in the server, and put them in the listview. Now I want this email addresses could be dragged from my listview to contacts in Outlook 2007.

could this be possible?

thanks and best regards

Reply to this comment
1. Anders Melander January 21st, 2010 at 15:59 32 +0
  Yes it is possible.
  
  There are two ways to do it:
  1. Create a vCard, either in a file or in-memory, and drag that to Outlook.
    Use the TDropFileSource component to drag a vCard file. See the VirtualFile demo for an example of how to drag an in-memory vCard.
  2. Create an in-memory instance of a Outlook contact COM object and drag that to Outlook.
    See the Outlook source demo for an example of how to drag Outlook items back into Outlook. The hard part with this solution is the construction of the Outlook contact COM object and I'm afraid I cannot provide any help beyond what the demo provides.
  The vCard approach is by far the easiest and I recommend that you use it if possible. You can easily test it with the VirtualFile demo.
  Reply to this comment
  1. Anders Melander January 25th, 2010 at 12:14 33 +0
    
    WRT messing with Outlook Contact objects I just remembered this old comment.
    
    (Comments wont nest below this level)
    
    Reply here

Jeff Y. January 22nd, 2010 at 19:11 34    +0

Hello. My program is using Version 4 of the toolkit, and, based on ExtractDemo, I've been working on having it allow the user to drag a .WAV file within the program onto a target location, including other apps that accept .WAV files dropped onto them.

My program renders the file at the time the file dropped to the target location, when DropFileSource1Drop is executed by my program.   This works fine for some apps, however, in testing, there are reports that it doesn't work for some apps.  One target app that I tested appears to require a fully-formed valid file to be present on disk at the time the mouse cursor is moved over it, otherwise the mouse cursor stays at "no drop allowed" cursor.   Windows Media Player had a similar problem, in that it required a file with the target name to be present on disk, but I was able to get my program to drop into WMP by creating a small dummy file with the target file name, before DropFileSource1.Files.Add and DropFileSource1.Execute are called.  Then, when the DropFileSource1Drop method is executed to do the actual drop, my program just erases the dummy file and re-creates it and WMP received it.

The problem: Unlike Windows Media Player, this other program requires the dummy .WAV file to be a VALID .WAV in order for the mouse cursor to indicate the program will accept the file, but if I try erase the file and then recreate it during DropFileSource1Drop, or if I have my program attempt to open the existing file and add to it, then it won't work because the other program (or windows) has taken control of the file and blocked my app from accessing it or erasing it.

Wondering if there is any solution to this problem?   How can I prevent the target app from taking control of the file before the DropFileSource1Drop is executed? Also I am curious how the target app even knows the name of the file when the mouse cursor is hovering over the app, but before DropFileSource1Drop is executed?

Thanks,

Jeff

Reply to this comment
1. Anders Melander January 22nd, 2010 at 20:46 35 +0
  The drop target can query the drop target about the data being dragged at any time during the drag operation. It does so using the IDataObject that is passed to it when IDropTarget.DragEnter is called.
  
  The solution to your problem is to create the source files if, and when, the target reads the file names from the drop source source's data object. Fortunately this is very easy: All you have to do is move the creation of the files from the OnDrop handler to the OnGetData event handler.
  There are a few things you need to be aware of though:
  1. The OnGetData event is fired each time the drop target calls IDataObject.GetData.
  2. The drop target can call IDataObject.GetData many times during a drag operation. Each call will fire the OnGetData event.
  3. Just because the drop target has called IDataObject.GetData does not mean that it will eventually accept the drop.
  The following changes implement the above in the ExtractDemo application:
  1. Add a flag that indicates if the files have been created:
    
    type TFormMain = class(TForm) ... private FHasExtracted: boolean; ... end;
  2. Initialize the flag when the drag starts:
    procedure TFormMain.ListView1MouseDown(Sender: TObject; Button: TMouseButton; Shift: TShiftState; X, Y: Integer); ... begin ... FHasExtracted := False; // Start the drag operation... DropFileSource1.Execute; ... end;
  3. Add a method, ExtractFiles, to create the files (once) and move the current implementation from the OnDropHandler to there:
    procedure TFormMain.ExtractFiles; var i: integer; begin if (FHasExtracted) then exit; // 'Extract' all the selected files into the temporary folder tree... for i := Listview1.Items.Count-1 downto 0 do if (Listview1.Items[i].Selected) then ExtractFile(i, FTempPath + Listview1.Items[i].Caption); FHasExtracted := True; end;
  4. Call the ExtractFiles method from the TDropFileSource.OnDrop handler:
    procedure TFormMain.DropFileSource1Drop(Sender: TObject; DragType: TDragType; var ContinueDrop: Boolean); begin // If the user actually dropped the filenames somewhere, we would now // have to extract the files from the archive. The files should be // extracted to the same path and filename as the ones we specified // in the drag operation. Otherwise the drop source will not be able // to find the files. ExtractFiles; // As soon as this method returns, the destination's (e.g. Explorer's) // DropTarget.OnDrop event will trigger and the destination will // start copying/moving the files. end;
  5. Call ExtractFiles from the TDropFileSource.OnGetData handler if the target asks for a list of filenames:
    //////////////////////////////////////////////////////////////////////////////// // // OnGetData handler. // //////////////////////////////////////////////////////////////////////////////// // Executes when the drop target requests data from the drop source. // // This is a good place to create the physical files so they are actually // present when the filenames are returned to the drop target. // Even though it would be more efficient to only create the files in the OnDrop // handler, some drop targets expect the files to be present and valid at the // time the cursor enters the drop target (i.e. at the time IDataObject.GetData // is first called). //////////////////////////////////////////////////////////////////////////////// procedure TFormMain.DropFileSource1GetData(Sender: TObject; const FormatEtc: tagFORMATETC; out Medium: tagSTGMEDIUM; var Handled: Boolean); begin if (FormatEtc.cfFormat = CF_HDROP) then ExtractFiles; end;
  I hope this makes sense.
  Reply to this comment

Jeff Y. January 23rd, 2010 at 00:47 36 +0

Makes sense. Thanks.

Reply to this comment

Ray January 25th, 2010 at 21:31 37 +0

Hi! I've found your components tonight and am amazed. Thanks for the massive amount of work. However, I have to issues trying to simulate file-Drag&Drop from my application to a foreign target application that does not accept data from remote otherwise:

1. Is it possible at all to programatically drag and drop files to the target without moving the mouse cursor to the target "in real-time" with SetCursorPos?

2. The target seems to accept drops from Windows Explorer only. What is so special about Explorer that it can be identified by the target? How can I mimic Explorer's behaviour? Tomorrow, I will use your Source and Target analyzers to find out differences between my DataObjects and those of Explorer. Anyway, if you have an idea, any help is appreciated.

Reply to this comment
1. Anders Melander January 26th, 2010 at 00:41 38 +0
  1. There's no "supported" way of emulating a drag operation, but you can try this old hack…
  2. I can imagine several different ways the drop target can verify if Explorer is the drop source:
    
    It can examine the name of the active process.
    During a drag from Explorer it will most often be the active process. It is however possible to change the active process during a drag with Alt+Tab or by hovering over the task bar.
    
    It can check for various clipboard formats that are only used by Explorer. E.g. InShellDragLoop and Shell Object Offsets.
    The target components does supply the InShellDragLoop format automatically but not the Shell Object Offsets format.
  Reply to this comment

Gerry January 26th, 2010 at 21:45 39

Hello, i just tried this one with D2005, using the include path to the source. I took that TargetDemo of the Demos, and modified it, since i can't include packages to my Delphi IDE because of the Delphi version.This one works fine with D5000 ! You should add something like the following, if you can't add packages like me:

procedure TForm1.FormCreate(Sender: TObject);
begin
  DropFileTarget1 := TDropFileTarget.Create(self);
  DropFileTarget1.Enabled := true;
  DropFileTarget1.OnDrop := DropFileTarget1Drop;
  DropFileTarget1.DragTypes := [dtCopy, dtMove, dtLink];
  DropFileTarget1.Target := Listview1;
  DropFileTarget1.OptimizedMove := True;
end;
 
procedure TForm1.FormDestroy(Sender: TObject);
begin
  DropFileTarget1.Free;
end;

Reply to this comment

Anders Melander January 29th, 2010 at 22:10 40 +0
I have released version 5.1.
- Changelog
- Download
All known bugs and problems fixed.
Reply to this comment

Phil Chimbolo January 31st, 2010 at 20:23 41 +0

I have confirmed that these components ARE compatible with Delphi 2006.

By the way… nice job!!!! And much appreciated.

Reply to this comment
1. Anders Melander January 31st, 2010 at 21:02 42 +0
  
  Thanks. I have updated the list.
  
  Reply to this comment

lovethisgame February 1st, 2010 at 04:09 43 +0

Is there a way to know the source application?

I mean whether there is a way to know from which application, say WORD, EXCEL, Internet Explorer or FireFox, the data is dragged?

Thanks in advance.

Reply to this comment
1. Anders Melander February 1st, 2010 at 08:10 44 +0
  
  No - not really.
  
  You can examine the data formats offered by the source application and from that you can make an educated guess, but it's only a guess and you will have to have analyzed the different drop sources beforehand to learn of their "fingerprint".
  
  Reply to this comment

ken February 2nd, 2010 at 00:06 45 +0

Downloaded the DragDrop components, awesome. Ran the Outlook demo with Delphi 6, everything worked great. Ran the Outlook demo with Delphi 2010, the opening of attachements isn't working (ActionAttachmentOpenExecute). Saving the attachment appears to be failing, yet I'm not getting any errors. I have rights to the directory, not an expert with streams….any ideas?

Reply to this comment
1. Anders Melander February 5th, 2010 at 15:28 46 +0
  I have reproduced and fixed the problem.
  
  The function used to create the attachment file, OpenStreamOnFile(), was declared wrong. The filename parameter must be a PAnsiChar even when Unicode is used.
  
  To correct the problem you can cast the filename to a AnsiString and then to a PAnsiChar in ActionAttachmentOpenExecute:
  OleCheck(OpenStreamOnFile(PAllocateBuffer(@MAPIAllocateBuffer), PFreeBuffer(@MAPIFreeBuffer), // Filename must be AnsiChar even when using Unicode. STGM_CREATE or STGM_READWRITE, PAnsiChar(AnsiString(FileName)), nil, DestStream));
  Reply to this comment

Yuri Maggi February 3rd, 2010 at 02:50 47 +0

Great suite.
I am trying to make some simple copy/paste but I would like to copy a stream into the clipboard to be paste onto Explorer as a file. Is there any specific example in which this capability can be visualized ?
I am also thinking about how to create a shell handler to transfer this files directly by drag'n'drop (my application actually has the files centralized in a server and each time I need to open or copy them it is a remote operation, so they need to be downloaded first). Will appreciate any help… Thanks !

Reply to this comment
1. Anders Melander February 5th, 2010 at 16:51 48 +0
  
  The VirtualFileStream example does what you need; It demonstrates how to drag data as a file stream or copy it onto the clipboard.
  
  Wrt your second scenarion, check out the AsyncFTPClient example. It drags files from a remote FTP server. The files are transferred from the server on-demand as the drop source requests them.
  I cannot help you with the Shell Namespace Extension as I have no experience with that. There are 3rd party solutions that can help with that if you do not wish to get your hands dirty.
  
  Reply to this comment

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The Drag and Drop Component Suite for Delphi

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FAQ - Frequently Asked Questions

When dragging a file from my application to the Explorer, how can I determine the folder where the file is dropped?

What is the difference between the drop source components’ `AllowAsyncTransfer` property and the `Execute` methods’ `Asynchronous` parameter?

What is “Optimized Move”?

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MelanderBlog

The Drag and Drop Component Suite for Delphi

Status

Features

Components

License

Requirements

C++ Builder

Download

Old versions

Installation

Uninstallation

Change log

FAQ - Frequently Asked Questions

When dragging a file from my application to the Explorer, how can I determine the folder where the file is dropped?

What is the difference between the drop source components’ AllowAsyncTransfer property and the Execute methods’ Asynchronous parameter?

What is “Optimized Move”?

48 comments »

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What is the difference between the drop source components’ `AllowAsyncTransfer` property and the `Execute` methods’ `Asynchronous` parameter?